Torque Required to Tighten M4 Brass Screw to Brass Plate

Mechanical properties of the 2 brass parts ? If not know the recommandation can be too far from good and the risk to break the screw too big.

Define, "tighten".

Just like almost everybody else who asks "how much torque is required...", you're woefully lacking in prerequisite data :

Before you seek a target torque, you need to define how tight your screw has to be.

Then, you have to define how much friction might be encountered during the tightening procedure.

Be very careful: If some "expert" were to give you a torque value without asking for the above information, you and your cohort would end up screwing blindly in the dark